Expanding-shoe brake



oct. 16, '1928.A

A -G. FORNACA EXPANDING SHOE BRAKE Filed Sept. 20, 1926 Parental oci.16, 192s.

GUIDO roRNAoA, or TURIN, many.

EXPANDING-SHOE BRAKE.

Application led September 20, 1926, Serial No. 136,593, and in ItalySeptember 28, 1925.

This invention relates to expanding Ashoe brakes of the kind in whichthe actual'f braking effort is created automatically by the rotation ofthe brake drum in either direction, when the shoes are expanded. Its

object is an improved arrangementfor supporting and centering the shoes.i

In accordance with my present invention a brake of the kind stated hasthe pivot ends of the two shoes made fork-shaped and supported byabearing mounted for oscillation on a fixed pivot. and through whichfork shaped ends the shoe coming first into contact with the drum in thedirection of rotation of the brake drum transmits to the other shoe thethrust it receives from the'drum; but both shoes are free to make themovement required to bring them inv contact with the drum. l

By way of example, a constructional form of the improved brake isillustrated on the accompanying drawing.

1 and 2 denote the fork-shaped ends of the brake shoes 3 and 4,supported by a bearing 5 capable ot oscillating on the pivot 6 securedto the fixed shoe-anchor plate, This arrangement allows of adisplacement of the' shoes as well as their oscillation on the pivot 6.

The shoes transmit the thrust they receive from the drum through thebevelled end surfaces 7 kept in contact by means of the springs 8 and 9.n

A spring 10 holds the two shoes centered with respect to the drum in theinactive position shown on the drawing, but allows a sufficientdisplacement of said shoes in both directions for the operation of thebrake.

During expansion the shoes turn about the bevelled end surfaces 7.

Reference 13 denotes reinforcing ribs or fins on the forked ends of theshoes.

The spring 10 surrounds a bolt 15 and both bolt and spring pass throughan opening,y in the support or pivot 6. The ybearing 5 that oscillateson the pivot pin 6 has at its upper end a shoulder 16 against which liesa washer 17 forming't-he upper seat for the spring 10. The lower end ofthe bearing 5 has a perforated cap 18 that forms, an abutme-nt for awasher 19 forming the lower seat for spring 10. The bolt 15 passesthrough both washers 17 and 19 and has a nut 20. vThe head of the bolt15 vis connected by a shackle 21 in the fork of the 5 `-upper shoe.

The two shoes 3 and 4 are cammed apart by the usual cam device at theirfree ends. At their rear or pivoted ends the springs 8 and 9 tend tohold the two shoes together at the pivot 6. YVhen the shoes are cammedapart at their free ends one or the other shoe may engage the brake drumfirst. Assume that shoe 3 is the first to engage the drum. This shoe isrocked on its cam surface 7 at a point eccentric to and outside ofpivotpin 6. Consequently bolt 15 is pulled upward, the. nut 20 engagingwasher 19 and causlng spring 10 to be compressed on the upper washer 17that is held stationary by the shoulder 16. This causes shoe 3 where itcontacts with shoe 4 to exert a pressure ou the pivot end of shoe 4l andcause it to engage the drum at its pivot end. This is eifectcd by thecam surfaces 7. lVhen the shoe 3 engages the drum it will be dragged bythe latter and push the pivotend of shoe 4 against the drum. Both shoesare free to more apart from the pivot 6 so that the entire surface ofeach shoe is free to engage the drum. When the brake is lreleased the.springs 8 and 9 pull the shoes toward one another and at the same timespring 10 pulls the pivot end of shoe 3 into its centered position withregard to pivot pin 6. The other .shoe 4 being caused to assume asimilar position as its surface is the meeting line of the two Shoes,contacts with the similar surface on the other shoe and under the actionof springs'S and 9.

That I claim is:

l. A vehicle brake having a brake drum, a pair of brake shoes forco-action therewith, and a fixed support for said shoes; in combinationwith co-acting cam surfaces on the mutual contacting faces of the shoesadjacent the support and forming a shift-ing pivot for the shoes as theymove bodily from the support and means to draw the shoes together whenreleased.

2. A vehiclebrake having a brake drum, a pair of brake shoes for coac'tion therewith and means to draw the shoes together when they arereleased; in combination with a fixed pivot pin, a bearing on said pin',a bolt passing through the bearingand pin, a spring between the bearingand bolt means to movably connect'the boltto one 4of the shoes.

port, and having a shoulder therein at one end, a bolt passing` throughsaid beating and support, a spring on the bolt abutting said shoulder, ashackle connecting one end of the bolt to one of the shoes and camsurfaces forming` extensions of the contacting surfaces of the shoesproviding a shifting pivot for the shoes as they move from the support.

In testimony that I claim the foregoing as my invention I have signed myname.

GUIDO FORNACA.

